Proving grounds should be gear normalised.
If you want to see who has the best guild mates, who can commit to the most punishing raid schedule, who has the most DKP and who has the most luck with drops................well hey that already exists and it is called "raiding".
I don't believe for one minute that random Joe on his fresh 90 tank will be able to go in there and get a top time with a "lucky" run. Such accusations would be unsporting and besides there are too many smart people playing this game who will theorycraft these encounters. These strategies will be posted on WoW community sites for everyone to see and the top times will be those that can most skilfully implement them.
I don't believe they should be a test of who has the correct enchants, gems and reforges either as 99% of players just rip that info from EJ or have addons that tell them what to do. Those are merely "marks for turning up".
I thought the purpose of proving grounds was to demonstrate individual class/role playing skill - something that isn't necessarily catered for by raids - remember we already have a test of who is "the best raider". Proving grounds with gear normalisation give the PVP'er or the casual player a chance to demonstrate their skills in comparison to their raiding cousins.
That rivalry between PVP'ers , Raiders and Casual players would add some real flavour and interest to the leaderboards.
Who knows, maybe there could be an upset and Mike B will survive longer than Lore or perhaps Gannon could do the pair of them! I understand that this puts pressure on the Lore's of this world as they have the most to lose due to the expectation that they will be the best. I feel that raiders should demonstrate some good sportsmanship and not request that other players are handicapped by something like gearing for which individual skill is only a component after all - and only a 4% to 10% component at most in raiding...